Between MCP, A2A, and ARD, WTF: How should companies think about the protocols at the heart of agentic AI?

Mary Branscombe's avatar

When @ironyuppie.com mentioned the new Agentic Resource Discovery for service discovery, my reaction was 'I just kind of worked out how MCP and A2A fit together, why do we need *another* protocol?' and then when I started looking into it, that isn't even all the proposed open agent protocols!

Mary Branscombe's avatar

part of this is the pre-Cambrian explosion of experimentation and eventually you get Ediacaran die-off back to what make sense; partly it's that enterprise vendors have both experience in service discovery and an obvious interest in defining how registries & directories of services for agents work

Mary Branscombe's avatar

enterprise vendors and the AI labs all want their protocols adopted; that means open governance and that means the AIAF: @maniksurtani.bsky.social explains to me how the foundation is navigating a list of protocols he expects to get longer before it gets shorter to build a stack for agent work

Mary Branscombe's avatar

MCP is the most mature of the agent protocols: @caitie.bsky.social tells me about MCP 2.0 and the new constructs coming to simplify long-running agents as well as how it fits in with A2A and ARD because they do have different roles and which you need is clearer once you understand what they each do

As usual, not everyone I talk to is on Bluesky (boo!), so some extra notes. We're used to having multiple protocols Papi Menon points out; Todd Segal and Junjie B. give me the technical details of how the three protocols complement each other and Matt Dickens explains how ARD not only improves MCP governance but also helps you avoid getting locked in to one model. It's David Mooter who gave me a mini maturity model for when to adopt each protocol (when you need it or you'll lose business by not having it).

Mary Branscombe's avatar

What everyone told me is that this is all still very new and we're making up a lot of this as we go along. But if you want to understand how to give agents connections to the tools and other agents that make them useful, waiting till it's all baked will leave you behind competitors who dive in now

The protocol proliferation problem: Making sense of the open agent stack
Between MCP, A2A, and ARD, WTF: How should companies think about the protocols at the heart of agentic AI?
https://www.thestack.technology/the-protocol-proliferation-problem-making-sense-of-the-open-agent-stack/
  • open agent protocols

  • MCP

  • A2A

  • ARD

  • ACP

  • AIAF

  • open governance